Brake



Sept 17, 1940- E. F. Lows-:KE ,2,214,967

BRAKE Filed Oct. 5, 1958 28 F l f6 5 INVENTOR.

few/Af 'z; @wf-ms- BY ATTORNEY.

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Patented Sept. 17, 194i()4 UNITED STATES PATENT OFFICE draulic Brake Compan poration of California.

y, Detroit, Mich., a cor- Application October 5, 1938, Serial No. 233,468

' s Claims. (ci. 18s-152,)

This invention relates to brakes, and' more particularly to brakes for motor vehicles.

An object of the invention is to provide a iiuid pressure actuated motor including opposed plstons. and means intermediate the pistons for trapping iluid so as to retain one of the pistons against movement toward its retracted position.

Another object of the invention is to providea iiuid pressure actuated motor for actuating the vfriction elements of a brake structure, and to so construct the same that at least one of the elements may be held against movement toward its retracted position during actuation ofthe brake.

Other objects and advantages ofthe invention will appear from the following description taken in connection with the drawing forming a part of this specification, and in whichv Fig. 1 is a vertical sectional view of a brake. embodying the invention;

Fig. 2 is a vlongitudinal sectional view of the iiuid pressure actuated motor; and

Fig. 3 is a cross-sectional view of the motor, substantially on line 3-3, Fig. 1.

Referring to the drawing for more specific details of the invention, I0 represents a xed support or backing plate adapted to be secured to an axle or to an axle housing, and associated with the backing plate is a rotatable drum I2 adapted to be secured to a Wheel.

A pair of corresponding interchangeable friction elements or shoes I4 and I6 are pivotally mounted on the backing plate. Each of the shoes includes a web I8 supporting a rim 2'0 having secured thereto a lining 22 suitable for cooperation with the drum.

Adjustable retractile stops 24 suitably arranged on the backing plate support the shoes in proper spaced relation to the drum when in retracted position, and a retractile spring 26 connecting the shoes serves to return the shoes to the retracted position and to retain them against the stops when in such position.

A fluid pressure actuated motor 28 mounted on the backing plate and connected to the shoes as by thrust pins 30 and 32 serves to actuate the shoes into engagement with the drum against the resistance of the retractile spring 26. The motor includes a cylinder 34 having a large chamber 36 and a relatively small chamber 38 arranged in axial alignment with one another and separated by a diaphragm 40 having an annular rib 42, the purpose of which will hereinafter appear, and a concentric opening 44 providing a communication between the chambers. The chamber 36 is provided with a port 46 connected as by a iiuid pressure delivery pipe or conduit 48 to a suitable source of uid pressure. The chamber 36- also has a-port 50 normally closed as by a bleeder screw 52, and, correspondingly, the small chamber 38 has a port 54 normally-closed by a con- I ventional bleeder screw, not shown.

A valve 56 in the chamber 36 is seated on the diaphragm 10 for control of the port 44. As shown, the valve includes a iiexible cup including a disk 58 normally supported on the diaphragm l0 with the annular rib 42 embedded therein so as to more effectively seal the disk to the diaphragm. The disk has a marginal lip 60 normally engaging the wall of the chamber 36 and a concentrically disposed opening 62, and a spring-rest 64 seated u in the cup has a plurality of openings 66 therethrough arranged in a circle the center of which is in the axis of the opening 62.

A piston 63 reciprocable in the chamber 36 has a recess in its back for thereception of the thrust 20 pin 30, and seated on the head of the piston is a sealing cup 10 held against displacement by a spring 12 interposed between the cup and the spring-rest 64. This spring also serves to retain the valve 56 Aon the diaphragm 40. Correspond- 25 ingly, a piston 14 reciprocable in the small chamber 38 has a recess in its back for the reception of the thrust pin 32, and seated on the head of this piston is a sealing cup 16 held against displacement byv a spring 16 interposed between the 30 cup and the diaphragm 40.

In a normal operation, when fluid under pressure enters the chamber 36, the valve 56 opens and a part of the iiuid passes through the valve into the chamber 38. 'I'his causes concomitant 35 actuation of the pistons 68 and 14, and this actuation of the pistons results in moving the shoes I4 and I6 from their position of rest on the stops 24 into engagement with the drum I2 against the resistance of the retractile spring 26, so as to effec- '40 tively apply the brake.

During a heavy or prolonged braking operation, the drun becomes distorted to a greater or less degree, duc to the greater effectiveness of the forward braking shoe because of its self-energizing characteristic. 'I'his distortion of the drum impairs the effectiveness of the brake, and this condition may be avoided by controlling the friction elements or shoes so as to offer substantial resistance to any distortion of the drum that may occur 50 during a braking operation. The desired control of the shoes may be eiiectively accomplished by interposing n simple valve 56 between the pistons 68 and 14 to trap the fluid in the small chamber 38 so as to retain the piston I14 against movement I6 and thereby inhibit movement of the reverse Upon conclusion of a braking operation, the

pressure on the fluid is released, whereupon the valve 56 opens and the shoes I4 and i6 are returned to their retracted position under the inuence of the retractile spring 26 connecting the shoes; and as the shoes return to their retracted positions, the pistons 88 and 'i4 are moved to their retracted positions on the stops. 24 against the resistance of the springs 12 and 18.

While this invention has been described in connection with certain specific embodiments, the principle involved is susceptible of numerous other applications that will readily occur to persons skilled in the art. The invention is, therefore, to be limited only as indicated by the scope of the appended claims.

Having thus described the various features of the invention, what I claim as new and desire to secure by Letters Patent is- 1. In a fluid pressure actuated brake, a motor comprising a large chamber and a relatively small chamber, a diaphragm between the chambers having an opening, a piston reciprocable in each of the chambers, and a two-way valve seated on the diaphragm within the large chamber for control of the opening.

2. In a uid pressure actuated brake, a motor comprising a cylinder having a large chamber and a relatively small chamber arranged concentrically of the large chamber, a diaphragm separating the chambers having an opening providing a communication between the chambers, a piston reciprocable in each of the chambers, and a two-way valve seated on the diaphragm within the large chamber for control of the opening. l

3. In a fluid pressure actuated brake, a `motor comprising a cylinder having a large chamber and a relatively small chamber arranged concentrically of the large chamber, a diaphragm separating the chambers having a concentric opening providing a communication between the chambers, an annular rib on the diaphragm extended into thelarge chamber, a two-way valve seated on the diaphragm for control of the opening including a flexible cup adapted to imbed the annular rib on the diaphragm, said cup having an opening therethrough, and a disk in the bottom of the-cup having openings therethrough oifset with relation to the opening in the cup.

4. In a fluid pressure actuated motor, a cylinder, opposed pistons movable therein, and a two-way valve between the pistons including a flexible sealing'cup having a concentric opening. and a member in the bottom of the cup having openings therethrough offset with respect to the opening in the cup.

5. In a uid pressure actuated motor for actuating the frictionelements of a brake, a cylinder having a large chamber and a small chamber, a piston reciprocable in each of the chambers, a two-way valve separating the chambers including a flexible cup seated on a shoulder at the junction of the chambers including a exible cup having a concentric opening, a spring-rest seated in the bottom of the cup having openings therethrough offset with relation to the opening in the cup, and a spring interposed between the spring-rest and one of the pistons.

6. A brake comprising a fixed support, 'a rotatable drum associated therewith, friction elements on the support for cooperation with the drum, a motor on the support including a cylinder, a diaphragm in the cylinder having an opening therethrough, said diaphragm dividing the cylinder into two chambers, pistons in the chambers connected respectively to the friction elements, and a iiuid pressure actuated valve on the diaphragm for control of the opening.

7. A brake comprising a fixed support, a rotatable drum associated therewith, friction elements on the support for cooperation with the drum, a motor on the support for actuating the friction elements including a double-diametral cylinder,

opposed pistons movable in the cylinder, and atwo-way valve in between the pistons including a flexible cup having a concentric opening and a spring-rest seated in the bottomof the cup having openings therethrough arranged in a circle surrounding the opening in the cup.

8. In a fluid pressure actuated motor, a cylinder, opposed pistons movable therein, a valve between the pistons including a sealing member having an opening therethrough, and a rigid member in the bottom of the sealing member having openings therethrough offset with respect to the opening in the sealing member.

ERWIN F. LOWEKE. 

